This is a 1/4 inch objective by Ross of London. In his History of the Microscope of 1867, Jabez Hogg describes this type of Ross objective. It has a correction collar for cover-glass thickness. This particular 1/4 inch objective is in very good condition, with only minor marks on the lacquer finish. It produces a very nice image, even when compared with much more modern optics. The objective and brass case are inscribed 1/4 In 100 Ross London
Zeiss GFL Microscope
Objective: Ross 1/4 inch
Ocular: Watson x8 Compensating
Brightfield
Camera: Canon Powershot S50
ISO50, 1/1250 sec, F8